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Need help with my Nytro running rough.

Dannel94

Newbie
Joined
Jan 29, 2023
Messages
9
Age
29
Location
Gävleborg
Country
Sweden
Snowmobile
Ockelbo 600
Yamaha nytro
Hi, bought a Nytro -09 MCX 270 for 4 weeks ago, grenaded the engine as soon as i got home. Put a new engine in and it was running awesome for about 1 week.

One morning i was going for a ride and started it up but it was only running on 2 cylinders so i checked fault codes and got a code 31(Cylinder 1 coil) so changed all coils but no difference, turned out it was the cables above the engine mount at the clutch side that had rub against the frame, so i taped it up and re routed it a bit.

Now it runs on 3 cylinders but is running rich(i think?).

It stutters and misses around 0-50% throttle, as soon as the boost are coming it runs great.

Have gone in diagnostic mode and tested the coils for ignition, tested the injectors and they click, i have checked TORS.

Tors was 17 on 0 throttle and 89 on full throttle, supposed to be 94 on full throttle but that shouldnt matter?

Changed all spark plugs for brand new CR9E today, gapped to 0.5mm but no diffrence.

When checking the plugs it looks like its running lean but looking at the oxygen meter it seems to be running rich..

AFR is saying 11-12.5 on idle, around 12 on 0-50% throttle and 11.5 full throttle. It keeps jumping to HTR mode and error code E9 also so idk if i can trust it anymore.

Could the computer box have been shorted when ignition cable 1 touched the frame?


Checking the pictures now it looks like spark plug #2 looks to be running leaner than the others
 

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Are you running fresh fuel? What are the plugs gapped at?
Your O2 sensor for the AFR gauge is probably crapping out. Make sure the power and ground to the gauge are good.
The MCX box is fine if it runs good under boost. Make sure you have a good clean pressure signal to both the OEM MAP sensor and the MCX box.
 
Are you running fresh fuel? What are the plugs gapped at?
Your O2 sensor for the AFR gauge is probably crapping out. Make sure the power and ground to the gauge are good.
The MCX box is fine if it runs good under boost. Make sure you have a good clean pressure signal to both the OEM MAP sensor and the MCX box.
Yes fresh premium 98(europe, sweden) fuel
Plugs gapped at 0.20 (0.5mm)
Wierd since the sensor and gauge is only 2 weeks old, maybe the soot killed it?
Will check power and ground to it.
 
The soot won't kill the sensor, lead in race fuels kills sensors. It coats the little pores in the sensor surface like a glaze. Another is if the sensor is run in a AFR that is severly rich, but the picture of your plugs disproves that. A sympton of a failing sensor is it will react very slowly and suggish from lean to rich.
Sounds like by what you mentioned your AFR gauge is jumping to HTR mode and error code E9, that you have a Innovate Wideband... HTR is the gauge start-up function where it is preheating the sensor element when it first turns on after detecting voltage, and E9 is a low voltage error code. You have an unstable 12v power supply that is dipping too low for the sensor, so it is losing 12v power intermittently and resetting or the voltage level drops low for too long. If it happens when you get on the boost, it's a voltage draw somewhere when the fuel system gets under a load and it's dragging the battery voltage at the gauge down too low. More likely an intermittent connectiion. Check your wiring to that gauge.
 
The soot won't kill the sensor, lead in race fuels kills sensors. It coats the little pores in the sensor surface like a glaze. Another is if the sensor is run in a AFR that is severly rich, but the picture of your plugs disproves that. A sympton of a failing sensor is it will react very slowly and suggish from lean to rich.
Sounds like by what you mentioned your AFR gauge is jumping to HTR mode and error code E9, that you have a Innovate Wideband... HTR is the gauge start-up function where it is preheating the sensor element when it first turns on after detecting voltage, and E9 is a low voltage error code. You have an unstable 12v power supply that is dipping too low for the sensor, so it is losing 12v power intermittently and resetting or the voltage level drops low for too long. If it happens when you get on the boost, it's a voltage draw somewhere when the fuel system gets under a load and it's dragging the battery voltage at the gauge down too low. More likely an intermittent connectiion. Check your wiring to that gauge.
Ok thanks. Checked 12v connection and it had some green stuff so I cleaned it.

I was thinking, it has started to act up when I try to start it now (at the same time the rest of the problems), the relay clicks but wont turn over the engine.

This started at the same time as the afr went crazy and misfire stuff. Almost sounds like the battery are going bad?

But the seller said it was a new battery.

With my luck the starter motor are going out, right after i put new engine in lol
 
Ok thanks. Checked 12v connection and it had some green stuff so I cleaned it.

I was thinking, it has started to act up when I try to start it now (at the same time the rest of the problems), the relay clicks but wont turn over the engine.

This started at the same time as the afr went crazy and misfire stuff. Almost sounds like the battery are going bad?

But the seller said it was a new battery.

With my luck the starter motor are going out, right after i put new engine in lol


Ok so i checked my cables where it had rubbed against the frame behind clutch and opened it up and taped the cables seperatly with electric tape. Then I measured resistance from the ECU to coils and looked like it was fine.
Tried to start it but it just clicked, put a wrench between start relay and it started(so I guess the relay are bad not the starter thank god).

Went for a ride and it seems to be running good now! I also shut off my hand warmers, incase it was battery problems.

The downside is the AFR still reading Rich numbers, 12.5-13 on idle. About 1 afr lower than i had before on the whole register except when boost starts building, then it reads normal numbers.

Im also having vibrations, can feel it in my footwell. Only around 4500-5300rpms.. this sled just keeps giving me #*$&@.

Jacked it up and fired it up, it starts to rock back and forth around 4500rpms, any place to start looking?
 
Check the speedometer side drive shaft bearing. If that is OK, then check the track drivers for damage and the driveshaft for run-out, it might be bent.
 


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